Reagent for measuring clotting time and method for stabilizing tissue factor

Abstract

The present invention provides a reagent for measuring clotting time including a nonionic surfactant, a nickel ion and a tissue factor. A method for stabilizing a tissue factor, and use of a nonionic surfactant and a nickel salt for stabilizing a tissue factor are also disclosed.

1. A method for stabilizing a tissue factor in a liquid reagent to maintain its biological activity during storage comprising the steps of coexisting a nonionic surfactant and a nickel ion with the tissue factor in water, and storing the liquid reagent for at least a week before use. 
     
     
       2. The method according to  claim 1 , wherein the nonionic surfactant is at least one selected from the group consisting of polyoxyethylene octyl phenyl ether and polyoxyethylene sorbitan ester. 
     
     
       3. The method according to  claim 1 , wherein the nickel ion is a nickel ion derived from at least one selected from the group consisting of nickel sulfate, nickel chloride, nickel nitrate and nickel acetate. 
     
     
       4. The method according to  claim 1 , wherein the tissue factor is derived from at least one selected from the group consisting of a human, cattle, a rabbit and a monkey. 
     
     
       5. The method according to  claim 1 , wherein the tissue factor is a genetic recombinant tissue factor prepared from a silkworm pupa. 
     
     
       6. A method for measuring clotting time, comprising steps of: mixing a plasma sample and a liquid reagent for measuring clotting time comprising water, a nonionic surfactant, a nickel salt and a tissue factor, wherein the liquid reagent has been stored for at least a week before being mixed with the plasma sample, and wherein the coexistence of the nonionic surfactant and nickel salt with the tissue factor in water during storage serves to stabilize the tissue factor by maintaining its biological activity; and
 measuring the clotting time of the mixture. 
 
     
     
       7. The method according to  claim 6 , wherein the nonionic surfactant is at least one selected from the group consisting of polyoxyethylene octyl phenyl ether and polyoxyethylene sorbitan ester. 
     
     
       8. The method according to  claim 6 , wherein the nickel salt is at least one selected from the group consisting of nickel sulfate, nickel chloride, nickel nitrate and nickel acetate.